sorttable bug: single-digit-dates

summary: handle dates with single digits
class: bug · bug (definitely needs fixing)
priority: medium · This should be fixed as soon as, but probably isn't important enough for the next release
fixed-in:
depends:

Interpret D/M/YYYY, D/MM/YYYY, M/DD/YYYY etc as dates; they currently aren’t treated as such.

Also handle more date formats: Finnish dates are dd.mm.yyyy.